A recordable disc drive performs optimal power calibration (hereinafter abbreviated to OPC) before recording data on a recordable optical disc. Thereafter an optimal write power is acquired to proceed the succeeding data recording. FIG. 1 illustrates information area of a recordable optical disc. According to the regulation of the Specification (i.e. Orange Book and so on), the information area 100 of the recordable optical disc is partitioned to Power Calibration Area (PCA) 10, Program Memory Area (PMA) 20, Lead-In Area 30, Program Area 40 and Lead-out Area 50. The optical pickup head of the recordable disc drive performs OPC in the Power Calibration Area, i.e. the laser diode of the optical pickup head emits laser beams with various writing power to form test patterns in the Power Calibration Area. Thereafter reproducing the test patterns formed because of the various writing power, the recordable disc drive determines an optimal writing power and an optimal write strategy, wherein the optimal write strategy represents the driving signal of the laser diode for forming marks on the tracks of the recordable optical disc.
However, the writing quality of the recordable optical disc recorded by the recordable disc drive adopting the calculated optimal writing power is not good because below reasons:
(1) There's a time limit when performing OPC and a space limit because of a limited Power Calibration Area (PCA) which is the area for performing OPC. Once the recordable disc drive can't perform OPC thoroughly, the recordable disc drive can adopt only a few of writing powers to form corresponding test patterns and calculate the optimal writing power with interpolation based on the quality of the test patterns
(2) The regulated Power Calibration Area (PCA) are located in the most inner and most outer areas of the recordable optical disc while the area between the most inner area and the most outer area is the Program Area where the recordable disc drive perform data recording. The dye thickness of the inner and outer Power Calibration Area (PCA) are not the same with the one of the Program Area due to manufacture variation of the recordable optical disc. Therefore, the writing quality of the recordable optical disc recorded with the optimal writing power calculated by the recordable disc drive may not be good.
(3) The inside temperature of the recordable disc drive is rising while data recording. Hence, the laser output power of the optical pickup head is descending due to the rising temperature. Therefore, the writing quality is getting worse because the prolonged recording process.
(4) Due to manufacture variation of the control chip and the optical pickup head of each recordable disc drive, the writing quality of each recordable disc drive varies. Thus, after data recording, even every recordable disc drive adopting the same write strategy, some recordable disc drives still have writing problem of bad quality.
To solve the above problems, disc drive manufactories usually adopt Running OPC which is performing OPC in the data area. That is, after the optimal write power is acquired in the Power Calibration Area (PCA), the recordable disc drive proceeds data recording in the program area. During the process of data recording, the recordable disc drive paused data recording after a fixed amount of data is recorded or after a fixed duration, and performs OPC based on the quality of the pre-recorded data, thereafter a modified optimal write power is acquired for the succeeded data recording. To be more specific, a fixed amount of data or a fixed duration is pre-set before Running OPC is performed. Therefore, there're some detecting positions in the program area of the recordable optical disc. For example, there're detecting positions a to i in the program area of the recordable optical disc as shown in FIG. 1. The recordable disc drive pauses data recording when the optical pickup head of the recordable disc drive reaches any of the detecting positions during the process of data recording. Then, the recordable disc drive performs OPC based on the pre-recorded data, and revises the optimal write power. Thereafter, the succeeded data recording is recorded with the modified optimal write power. Consequently, the recordable disc drive performs OPC in the program area of the recordable optical disc until the data recording is finished.
The Running OPC mentioned above improves the writing quality of the recordable optical disc effectively. However, because the recordable disc drive reaches every detecting position and performs Running OPC, the time spent for data recording are indeed prolonged. Therefore, a solution of effectively reducing the time spent for data recording and maintaining good writing quality becomes an important issue to be resolved.